Paging systems are commonly used to send messages from one location to another. In these systems, a pager requester at one location pages a receiving user at another remote site. The pager requester typically initiates a pager request using a common Dual Tone Multi Frequency (DTMF) telephone. The pager requests are then provided to communication lines and finally transmitted, for example, as part of an FM signal from an FM radio station to the receiving user. The paged individual uses a paging receiver to receive and decode the FM signal to extract the message. The paging receiver may be carried for example, in a watchlike device.
A variety of radio paging systems are in common use. One such system, described in Gaskill et al. U.S. Pat. No. 4,713,808, teaches the modulation of an FM subcarrier signal with packets of digital data. This signal is injected into a conventional exciter and then transmitted from the FM station to a plurality of paging receivers. This patent is incorporated herein by reference and made a part of this application.
One problem encountered by paging companies is the need to determine in advance the range and quality of radio paging signals that will be received at various sites from a particular transmitting radio station. It is extremely desirable to have such information before a financial commitment is made to enter a lease or other arrangement with the station. These companies also need to determine the quality of the paging signal that will be received at various sites in view of various environmental obstacles such as buildings mountains, and the like.
Similar information is also extremely useful in trouble shooting, for example in determining whether erroneous pager transmissions are the fault of the paging company or transmission equipment at the radio station.
Such paging test information is typically determined only after an actual paging system is installed at the FM station and radio paging signals have been transmitted to pager customers. This method is an ad hoc process and can lead to a commitment to stations which are not suitable for paging because of poor transmission characteristics or environmental obstacles. Unnecessary customer dissatisfaction with the quality of received pager requests is also a possible result.
Moreover the use of an actual on-line paging system for testing is also limited by the difficulty for an actual pager to initiate a range of tests (a) in a matter of seconds, (b) at a variety of locations (c) for several candidate stations simultaneously, and (d) under varying environmental conditions.
Further, the use of normal paging frequencies for testing could interfere with or complicate normal paging operations.